Make decorators.task, Task, PeriodicTask, apply* available from celery.py

celery/__init__.py

@@ -2,3 +2,7 @@
 from celery.distmeta import __version__, __author__, __contact__
 from celery.distmeta import __homepage__, __docformat__
 from celery.distmeta import VERSION, is_stable_release, version_with_meta
+
+from celery.decorators import task
+from celery.task.base import Task, PeriodicTask
+from celery.execute import apply_async, apply